function getZodiacSign($birth_date) {
    $bd = explode("-", $birth_date);
    $daymonth = $bd[1] . "-" . $bd[2];

    if ($daymonth >= '01-21' and $daymonth <= '02-20') {
        $zodiac = 'Aquarius';
    } elseif ($daymonth >= '02-21' and $daymonth <= '03-20') {
        $zodiac = 'Pisces';
    } elseif ($daymonth >= '03-21' and $daymonth <= '04-20') {
        $zodiac = 'Aries';
    } elseif ($daymonth >= '04-21' and $daymonth <= '05-20') {
        $zodiac = 'Taurus';
    } elseif ($daymonth >= '05-21' and $daymonth <= '06-21') {
        $zodiac = 'Gemini';
    } elseif ($daymonth >= '06-22' and $daymonth <= '07-22') {
        $zodiac = 'Cancer';
    } elseif ($daymonth >= '07-23' and $daymonth <= '08-23') {
        $zodiac = 'Leo';
    } elseif ($daymonth >= '08-24' and $daymonth <= '09-23') {
        $zodiac = 'Virgo';
    } elseif ($daymonth >= '09-24' and $daymonth <= '10-23') {
        $zodiac = 'Libra';
    } elseif ($daymonth >= '10-24' and $daymonth <= '11-22') {
        $zodiac = 'Scorpio';
    } elseif ($daymonth >= '11-23' and $daymonth <= '12-21') {
        $zodiac = 'Sagittarius';
    } else {
        $zodiac = 'Capricorn';
    }
    return $zodiac;
}

//Will return "Aquarius"
echo getZodiacSign('1982-01-27');